Mechanical timepiece finds favor especially in the upper class because of the delicate workmanship and accurate structure. Relying on the metallic movement therein, a mechanical timepiece usually can be used for quite a long time. Therefore, high-grade mechanical timepiece also has its collection value. However, it is commonly known that a mechanical timepiece may not be able to provide sufficiently precise timekeeping. People have been seeking methods for improving its precision for a long time.
Accurate and reliable timekeeping is a basic requirement for all types of timepieces. Particularly, for a timepiece using a mechanical movement, factors such as the structural design, material selection, processing technology, and assembling quality will possibly affect the accuracy. As a result, the stability of the mainspring torque, the smooth operation of the transmission system and the accuracy of the escapement regulator may vary in different timepieces. Among all the factors, parameters of the balance spring, for example the width, thickness, turns and working length affect the timekeeping most directly. With the development of the modern technology, the precision of a mechanical timepiece has been greatly improved. The acceptable error certified by Swiss Astronomical Observatory is −4 to +6 seconds per day, namely −2 to +3 minutes per month. The error of an ordinary mechanical timepiece is about 3 to 10 minutes per month. For those asking for high accuracy timekeeping, however, such error is unacceptable.
Mechanical watches have much more complicated structures compared with electronic watches and quartz watches. Hence, once an error of timekeeping occurs, a common user can hardly adjust the watch himself. However, bring it back to the manufacturer or delivering it to a professional technician will waste a lot of time and will also render high service costs.
In addition to the internal structure of the timepiece, the environmental conditions and the user's custom also have influences on the timekeeping of the mechanical timepiece. For example, temperature change will induce change of performance of the lubricating oil and balance spring. The magnetic field of the environment, when greater than 60 Oersted, will cause magnetization of certain components within the timepiece. Also, high humidity will cause oxidization and erosion of the components. Therefore, even after maintenance, it is also possible for the watch to produce a greater error. Frequent returning to the manufacturer for maintenance is obviously undesirable.
The international patent application WO01/48566 has disclosed a mechanical timepiece with a regulator pin operating mechanism. The mechanical timepiece of WO01/48566 comprises a time calculating unit for calculating time having a quartz oscillator forming an oscillation source; an IC circuit including a frequency dividing unit for inputting output signal from the oscillation of the quartz oscillator and for outputting a signal corresponding to time by frequency division of the signal, and an energy source for operating the IC circuit; a daily rate detection unit for detecting the daily rate of the mechanical timepiece; and a daily rate adjusting portion including a regulator pin, operating on the basis of the count signal calculated by the time calculating unit and operating state signal representing the daily rate detected by the daily rate detection unit. By rotating the regulator pin on the basis of the operating state signal in this manner, the oscillation cycle of the balance wheel is changed such that it is possible to precisely adjust the daily rate of the mechanical timepiece. It can be seen that the device of WO01/48566 has a complicated structure and the cost thereof is therefore high. Besides, WO01/48566 employs a quartz oscillator, which inevitably brings about the defects with a quartz watch, for example the lifespan of the cell is limited.